Government actions are observable in the COVID-19 data

April 7, 2020 – Reading time: 8 minutes

The CoE Analytics & Sensorics analyses on a regular base available COVID-19 data to give insights into possibilities and constraints of Data Analysis

Established as Think-Tank for statistics and data analysis, the CoE AS normally enables companies to understand themselves better by analyzing their data (process, metrology, manufacturing…) to extract hidden information and parameters.

With this project we want to share our daily analysis about the actual COVID-19 outbreak and about impacts of these statistics. Everyone shall have the opportunity to understand how decisions in politics, society and in our daily life may have an impact and why data can be interpreted in such different ways from different stakeholders.

Any additional comments, adds and corrections are gratefully received.

 

Most actual Data Analysis is performed on Data from John Hopkins University, as here data is updated several times per day thus always providing the most actual data, which is of great importance for news to be always up-to-date.

However, we here use the publicly available data of the Robert Koch Institute. These data are updated only once a day but provide for Data Analytics one advantage: The newly reported cases are not mapped to the current day, but the date on which the doctor diagnosed the infection is used. So, the curve of newly reported cases still changes over time some days afterwards, making Data Analytics a “living document” and on the same time leaves out one blurring parameter: the time between diagnosis at the doctor and appearance in reports of each state that differ often by several days (reporting delay, details can be found in the dashboard of the Robert Koch Institute).

Since the number of subsequently reported cases is decreasing asymptotically, analyses about the situation some days ago can be carried out with a higher quality and allow conclusions to be drawn, however less quickly.

Figures 1 and 2 show logarithmic visualisations of the daily reported and the accumulated COVID-19 cases displayed versus the reporting date. Figure 1 shows the reported COVID-19 cases and deaths against the reporting date. From the March 19^th onwards, it can be seen that the growth of newly reported cases decreases, which repeats after March 29^th, which is a clear indicator for the success of the contact prohibition as we will see in the following.

An additional observation that we have been able to make is a periodic behaviour of the curve. The periodicity is 7 days with the lowest value on each Sunday. It is of course explained by opening hours of doctors, laboratories and public health departments. This limits us to the extent that we cannot make reliable statements about the last seven days, but rather have to wait for a repetition of the cycle.

Figure 2 shows the accumulated cases against their respective reporting dates. Here, too, a bending of the curve can be seen from March 19^th and again from March 29^th onwards.

This also coincides with the three fitted exponential curves (note again the logarithmic scale, figure 3 presents the same graph using linear scale), which intersect each other on March 19^th and March 28^th.

The doubling time has increased to 9.692 days at the transition from the grey to the green curve, which means that it takes about 10 days for the number of reported infections to double. The government wants a doubling period of far more than 10 days until the current measures can be relaxed. So we are on the right track.

Taking into account the median incubation time of COVID-19 of 5-6 days (source), the kink in the growth rate on March 19^th may be linked to the recommendation of Minister Jens Spahn to do his work in his home office. It is likely, however, that the data situation does not allow any statement about this, since the actual system is much more complex. Effects that have an influence on the propagation rate include

• Cancellation of flights and closure of borders
• Quarantine and rapid response by health authorities to break the chain of infection
• Increasing uncertainty of the population and social isolation
• The possibility to efficiently reduce the probability of infection with SARS-CoV-2 by washing hands
• Increasing infestation of social groups
• Forced leave and short-time work

However, the kink at March 29th is clearly related to the begin of the contact prohibition at March 22^nd, because the time difference is in the regime of the median incubation time. Therefore, we can confirm that the actions of the government have been successful in that they have significantly increased the doubling time. As the maximal incubation time of COVID-19 is 14 days, we expect that the curve will flatten even more over the current week.

Martin Eichner, epidemiologist from Tübingen and co-responsible for the online COVID 19 simulation, was interviewed by Tagesschau.de (Interview in German). The core statement is that the current contact ban does not solve the problem in any way, but only postpones it into the future, as the central problem of missing immunity remains. The goal of the contact ban cannot be to completely survive COVID-19, but only to delay the spread of the disease until a vaccine is available. However, as this is expected to take until the end of the year, the contact ban (if continued until then) will cause considerable social, economic and financial damage, which may not be in proportion to the benefits of contact ban (the number of deaths may not necessarily be lower). Eichner recommends propagation in waves, i.e. one takes the health system to its limits and then restricts public life incomparably harshly until the situation calms down again. This is repeated until the infestation of the population has reached 70%. But even this will be a huge burden on society.

To make the case numbers of the federal states comparable, the so-called incidence is used. The incidence represents the number of cases per 100,000 inhabitants (see Figure 4).

The population figures of the Länder (in 100,000 inhabitants) are shown in Table 1, middle column.

Looking at the incidences of the individual federal states, three main groups emerge over time:

• High incidence: Hamburg, Baden-Württemberg, Bavaria and Saarland
• Medium incidence: North Rhine-Westphalia, Berlin and Rhineland-Palatinate
• Low incidence: all other federal states

This suggests that Hamburg, Baden-Württemberg, Bavaria and Saarland are particularly affected by COVID-19 and have a higher rate of spread than the other German states.

What the incidence does not take into account, however, is the fact that the probability of infection is not the same for the different federal states. Since a distance of more than 2 m provides significant protection against infection, the probability of infection must be higher for more densely populated areas than for sparsely populated regions. If the cases are presented in relation to population density (simplified called „case density“ and standardized to the population density of Berlin), a different picture emerges (Figure 5):

• Bavaria now has the highest case density, followed by Baden-Württemberg
• North Rhine-Westphalia and Lower Saxony will follow later
• Hamburg (previously particularly affected) and all other federal states have relatively low case densities

The spread of COVID-19 is therefore particularly strong in Bavaria and to a lesser extent in Baden-Württemberg. The proximity to Italy and France could have a significant influence on this rate. However, additional influences are also the settlement of large corporations in these regions (Bosch, Zeiss, BMW, Audi, Daimler, etc.), which have many plants in the Asian countries and thus could have favoured the probability of transmission at the beginning. However, it is not possible to make reliable statements on these contributions on the basis of the data.

A research of the Bavarian Broadcasting Corporation attests the ski tourism to Ischgl/Tyrol a contribution not to be underestimated. In comparison to the calculated case densities, it should follow that the number of unrecorded cases (see BR’s visualisation) must have been particularly high in Bavaria. This is, however, statistically very unlikely, so the Ischgl case cannot be central to the significantly higher spread in Bavaria.

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Disclaimer

The presented analysis is based upon the data provided by the Robert Koch Institute. This data is updated daily (see status). The statements, which we derived today, may already be invalidated through new data provided tomorrow. We try to keep this analysis as up-to-date as possible.

Because not every health department updates their data during the weekends, data updates provided by the Robert Koch Institute on Sun- and Monday cannot be trusted and will be ignored for our analysis. The next update will be performed on Tuesday.

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Data reference

Reference: Robert Koch-Institut (RKI), dl-de/by-2-0

The data are the „Case Figures in Germany“ of the Robert Koch Institute (RKI) and are available under the Open Data Data License Germany – Attribution – Version 2.0.